The invention is directed to the use of aqueous L-lysine solutions having an L-lysine content between 30 and 80 weight percent for supplementing feeds and industrially produced mixed feeds with L-lysine.
Industrially produced mixed feeds serve particularly as foods for various agriculturally useful animals, such as poultry, swine, and cattle, but also are used as foods for household animals. The feed in each case as a rule contains all the necessary nutrients needed for the corresponding type of animal in weighed and sufficient amounts. There are known various individual feeding (or foddering) agents, e.g., soybean meal, corn, other types of vegetables, post milling products such as corn gluten or corn gluten meal, fish meal, meat meal, fatty feed, molasses, calcium acid phosphate, cattle salt, as well as other components of plant, animal, or mineral origin. Additionally, mixed feeds contain material which are added to improve the nutritional quality of the rations. For this purpose, there can be mentioned aminoacids such as L-lysine as well as minerals, trace elements, and preservatives.
The composition of the mixed feed is subject to changes depending on the supply and price of the components. However, the formula must always be so shaped that the nutrient content corresponds to the requirements of the animals in each case.
The various individual feeding materials and additives first are present as individual components. Depending on their nature, they must be prepared, e.g., by purification, drying, grinding, crushing. If the individual components have the necessary properties, the actual mixing process is carried out in a mixing plant suitable therefor. Thereby, the individual mixing components are different depending on the size of the plant. To produce a homogeneous mixture, there is required a sufficient exactitude in the mixing. For components which are present in the finished mixed feed only in small concentration under certain circumstances the production of a correspondingly more highly concentrated premixture is indispensable. Finished mixed feeds can be employed in the form of meal or also as pellets.
Already for a long time the essential aminoacid L-lysine has been used to a considerable extent as an additive in industrially produced mixed feeds for poultry, swine, and other animals. Thereby, however, there is not employed the crystalline aminoacid L-lysine in pure form since the L-lysine in free form is difficult to crystallize, exhibits strongly hygroscopic properties, absorbs carbon dioxide form the air, has an extremely unpleasant odor, and is inclined to decompose.
Rather, there were employed concentrates which besides the L-lysine formed by fermentation still contain the entire biomass obtained during the fermentation process or at least a part of the biomass (German patent 2357119 or East German patent 139205). In a given case, this type of concentrate also contains mineral additives such as lime, magnesium carbonate, silica, or silicates (German OS 3032618). The actual content of such concentrates of L-lysine accordingly is relatively small.
Therefore, generally for the supplementation of industrially produced mixed fodders with L-lysine, there is used L-lysine monohydrochloride. This monohydrochloride is a stable, easy to crystallize compound which is neither hygroscopic nor has unpleasant odor properties. Especially, L-lysine monohydrochloride is not inclined to decompose. Of course, its production is connected with additional material and process expense.
However, the use of L-lysine monohydrochloride for supplementing feeds and mixed feeds with L-lysine has the disadvantage that in common with the increase in content of L-lysine in the mixed feed, the content of chloride is also increased. Generally, this is not desired. Thus, the "National Research Council", for example, recommends for poultry feed a content of 0.08% chloride with a content of sodium of 0.15% and of potassium of 0.1 to 0.2% ("Nutrient Requirements of Poultry", Washington, D.C., 1977). The content of sodium, potassium, and chloride influences not only the acid-base equilibrium which through metabolic acidosis produced by increased chloride content leads to a depression of the rate of growth and feed consumption (Calvert, Poultry Science, Vol. 60, pages 1468-1472 (1981)) and also influences the Vitamin D- metabolism and the bone growth.
The ratio of lysine to chloride also plays a special role. According to Calvert, Poultry Science, Vol. 60, pages 1468-1472 (1981), e.g., the lysine-arginine antagonism which occurs especially in rations which are poor in arginine, is strengthened by increased chloride content. This leads to reduced feed intake and reduced growth. In feeding experiments with crystalline aminoacid diets, even the positive effect of the aminoacid addition is lost entirely if the aminoacids are employed as hydrochlorides and a chloride excess results (Proc. Nutr. Soc., Vol. 40, page 285 (1981)). For these reasons, a chloride free form of L-lysine for supplementing feeds and mixed feeds is very much desired.